This invention relates to a method of removing or preventing the accumulation of retained mucous secretions from the middle ear of a patient by administering certain uridine, adenosine, or cytidine triphosphates.
Otitis media (OM) is a viral or bacterial infection of the middle ear primarily, but not exclusively, afflicting children under three years of age. It is characterized by the presence of congested fluid in the middle ear and is usually precipitated by an infection in the respiratory tract which spreads into the middle ear via the nasopharnyx and eustachian tube. The incidence of OM is increasingxe2x80x94annual physician""s office visits for OM have increased 150% from 1975 through 1990 (L. McCraig and J. Hughes, JAMA 273(3), 214-19 (1995)). This is most likely due to increased use of large-group day care facilities, where children are exposed to more respiratory pathogens. Approximately 25-40 million office visits are made each year for diagnosis and treatment of OM, and by age three, approximately 75% of children will have had at least one episode of acute OM (with the maximum incidence in children 6-24 months of age) (J. Klein, Clin Infect Dis 19, 823-33 (1994)). Anatomically, the eustachian tubes in infants are shorter, wider, and lie more horizontally than in older children and adults, facilitating the spread of pathogens from the nasopharnyx to the middle ear (L. Schwartz and R. Brown, Arch Intern Med 152, 2301-04 (1992)). The infection evokes an inflammatory response in the mucosal tissue of the eustachian tube and middle ear, resulting in fluid effusion in the middle ear. The resulting fluid is viscous and pus-filled, making normal mucociliary movement of the fluid difficult, and inflammation of the eustachian tube at its narrowest point, the isthmus, effectively blocks drainage of the fluid into the nasopharnyx (J. Klein, supra (1994)). Middle ear congestion can be expected to cause significant pain, dizziness, and hearing impairment in the patient; the average hearing loss from the fluid accumulation is 25 decibels. This is of particular concern in very young children because impairment of hearing could delay or seriously impede aspects of normal cognitive development which are dependent upon exposure to language and social interaction (D. Teele, et al. J. Infect Dis 1621, 685-94 (1990)). Other potential (but uncommon) sequelae of OM include mastoiditis, meningitis, extradural abscess, subdural empyema, brain abscess, and lateral sinus thrombosis.
About 80-90% of OM effusions eventually resolve spontaneously following antibiotic therapy; the process may take as long as three months. However, congestion in the middle ear may persist for weeks or even months beyond sterilization of this fluid with antibiotics due to a continued hypersecretory state of the mucous-producing cells. (S. Wintermeyer and M. Nahata, Annals of Pharmocotherapy 28, 1089-99 (1994)). The cause of this persistent hypersecretory state is not well understood but may relate to unrelieved underlying eustacian tube obstruction. As a further impediment to treatment, the effectiveness of antibiotic therapy is decreasing on account of growing bacterial resistance to antibiotics (M. Poole, Pediatr Infect Dis J. 14(4), 523-26 (1995)). If middle ear congestion persists for more than three months, surgery is commonly performed to insert a typanostomy tube to ventilate the middle ear of the patient (K. Grundfast, Arch Otolaryngol Head Neck Surg, 120, 797-98 (1994)). Tympanostomy surgery is now the second most frequent surgical procedure in children (after circumcision) (J. Klein, supra (1994)). The tube allows drainage of the fluid out of the ear and eventual resolution of the disease in a vast majority of chronic cases. However, the surgery is costly ( greater than $2,000), and requires administering general anesthesia, a particular concern in infant patients. Furthermore, potential (but uncommon) sequelae of the surgery include persistent otorrhea, permanent perforation or scarring of the tympanic membrane, and cholesteatoma (a cyst-like sac filled with keratin debris that can occlude the middle ear and erode surrounding structures) (J. Klein, supra (1995)).
Thus, as a result of the decreasing effectiveness of antibiotic therapy due to bacterial resistance and the high costs and risks associated with typanostomy surgery, medical researchers have sought to develop other effective therapies for this increasingly prevalent disease. A French biotechnology company, Laboratoires SYNTHELABO FRANCE, has developed a method of treating nasal mucous fluid congestion under the trademark name rhinATP(trademark) which uses adenosine triphosphate (ATP) as the active compound. This technology was licensed under U.S. Pat. No. 5,420,116 (applicant intends the disclosure of this and all other patent references and publications cited herein be incorporated herein by reference). Their method of treatment comprises administering ATP to the nasal cavity via nasal spray or nasal drops. Uridine triphosphate (UTP) and adenine triphosphate (ATP) have also been shown to effect the ion transport activity of human airway epithelial cells, as described in U.S. Pat. No. 5,292,498. Specifically, UTP and ATP induce chloride and water secretion by the lung epithelial cells of cystic fibrosis patients, helping to liquify and facilitate transport of the highly viscous airway surface mucus that characterizes this disease. It has also been found that UTP and ATP stimulate the ciliary beat frequency in lung epithelial cells, further facilitating the transport of mucus from the lungs of cystic fibrosis patients. See, R. Boucher, et al., Adenosine and Adenine Nucleotides: From Molecular Biology to Integrative Physiology, p. 525-532 entitled xe2x80x9cMechanisms and Therapeutic Actions of Uridine Triphosphates in the Lungxe2x80x9d (L. Belardinelli, et al. ed., Alumwer Academic Publishers, Boston 1995); see also, L. Gheber, et al., J. Membrane Biol. 147, 83-93 (1995). Applicant has discovered that the high viscosity of the retained middle ear fluid in OM patients can be alleviated by administering UTP and its related compounds, as well as other nucleoside phosphates such as: adenosine 5xe2x80x2-triphosphate (ATP); cytidine 5xe2x80x2-triphosphate (CTP); 1,N6-ethenoadosine triphosphate; adenosine 1-oxide triphosphate; 3,N4-ethenocytidine triphosphate; P1,P4-di(adenosine-5xe2x80x2) tetraphosphate (A2P4); or P1,P4-di(uridine5xe2x80x2) tetraphosphate (U2P4) to the site of fluid blockage.
A method of treating otitis media in a subject in need of such treatment is disclosed. The method comprises administering to the middle ear of the subject a compound of Formula I, or a pharmaceutically acceptable salt thereof, in an amount effective to promote fluid drainage from the middle ear by hydrating mucous secretions in the middle ear and by increasing ciliary beat frequency in the middle ear and eustachian tube: 
wherein:
X1, X2, and X3 are each independently either Oxe2x88x92 or Sxe2x88x92. Preferably, X2 and X3 are Oxe2x88x92.
R1 is O, imido, methylene, or dihalomethylene (e.g., dichloromethylene, diflouromethylene). Preferably, R1 is oxygen or difluoromethylene.
R2 is H or Br. Preferably, R2 is H. Particularly preferred compounds of Formula I are uridine 5xe2x80x2-triphosphate (UTP) and uridine 5xe2x80x2-O-(3-thiotriphosphate) (UTPxcex3S).
Formula I is the preferred embodiment of the compound, however, the method of the present invention can also include administering a compound of Formula II (adenosine 5xe2x80x2 triphosphate [ATP] or 1,N6-ethenoadenosine triphosphate or adenosine 1-oxide triphosphate), or Formula III (cytidine 5xe2x80x2 triphosphate [CTP] or 3,N4-ethenocytidine triphosphate), or Formula IV (P1,P4-di(adenosine-5xe2x80x2) tetraphosphate (A2P4) or P1,P4 di(uridine-5xe2x80x2) tetraphosphate (U2P4). 
wherein:
R1, X1, X2, and X3 are defined as in Formula I.
R3 and R4 are H while R2 is nothing and there is a double bond between N-1 and C-6 (adenine), or
R3 and R4 are H while R2 is O and there is a double bond between N-1 and C-6 (adenine 1-oxide), or
R3, R4 and R2 taken together are xe2x80x94CHxe2x95x90CHxe2x80x94, forming a ring from N-6 to N-1 with a double bond between N-6 and C-6 (1,N6-ethenoadenine). 
wherein:
R1, X1, X2, and X3 are defined as in Formula I.
R5 and R6 are H while R7 is nothing and there is a double bond between N-3 and C-4 (cytosine), or,
R5, R6 and R7 taken together are xe2x80x94CHxe2x95x90CHxe2x80x94, forming a ring from N-3 to N-4 with a double bond between N-4 and C-4 (3,N4-ethenocytosine). 
wherein:
B is adenine or uracil.
A second aspect of the present invention is a pharmaceutical formulation containing the compound of Formula I, II, III, or IV in an amount effective to promote fluid drainage from the middle ear by hydrating the mucous secretions in the middle ear and by increasing the ciliary beat frequency in the middle ear and eustachian tube, in a pharmaceutically acceptable carrier.
A third aspect of the present invention is the use of the active compounds disclosed herein for the manufacture of a medicament for the therapeutic hydration of mucous secretions in the middle ear and for the activation of ciliary beat frequency in the middle ear and eustachian tube of a patient in need of such treatment.
The method of the present invention may be used to promote drainage of congested fluid from the middle and external ear of a subject in need of such treatment for any reason, including (but not limited to) retained secretions arising from middle and external ear diseases such as otitis media, acute otitis media, otitis media with persistent effusion, serous otitis media (arising from an unresolved acute infection, an allergic reaction, or barotrauma such as from rapid descent in an aircraft), or otitis externa. The method of the present invention may also be used to treat inner ear disease, including (but not limited to) Meniere""s Disease. The present invention induces drainage of middle ear mucous secretions by hydrating the retained secretions and by increasing the ciliary beat frequency of cilia on the surface of the middle ear and eustachian tube. Hydration of the mucous secretions decreases their viscosity, allowing them to be more easily transported from the middle ear and eustachian tube to the nasopharnyx via mucociliary action. Additionally, the present invention accelerates this mucociliary action, further facilitating drainage of retained middle ear secretions into the nasopharnyx.
The present invention is concerned primarily with the treatment of human subjects, but may also be employed for the treatment of other mammalian subjects, such as dogs and cats, for veterinary purposes.
Compounds illustrative of the compounds of Formula I above include: (a) uridine 5xe2x80x2-triphosphate (UTP); (b) uridine 5xe2x80x2-O-(3-thiotriphosphate) (UTPxcex3S); and (c) 5-bromo-uridine 5xe2x80x2-triphosphate (5-BrUTP). These compounds are known or may be made in accordance with known procedures, or variations thereof which will be apparent to those skilled in the art. See generally N. Cusack and S. Hourani, Annals N.Y. Acad. Sci. 603, 172-81 (entitled xe2x80x9cBiological Actions of Extracellular ATPxe2x80x9d). For example, UTP may be made in the manner described in Kenner, et al., J. Chem. Soc. 1954, 2288; or Hall and Khorana, J. Am. Chem. Soc. 76, 5056 (1954). See Merck Index, Monograph No. 9795 (11th Ed. 1989). UTPxcex3S may be made in the manner described in R. S. Goody and F. Eckstein, J. Am. Chem. Soc. 93, 6252 (1971).
For simplicity, Formula I herein illustrates uridine triphosphate active compounds in the naturally occuring D configuration, but the present invention also encompasses compounds in the L configuration, and mixtures of compounds in the D and L configurations, unless otherwise specified. The naturally occuring D configuration is preferred.
Compounds illustrative of the compounds of Formula II above include (a) adenosine 5xe2x80x2-triphosphate (ATP) and (b) 1,N6-ethenoadenosine triphosphate. Compounds illustrative of the compounds of Formula III above include (a) cytidine 5xe2x80x2-triphosphate and (b) 3,N4-ethenocytidine triphosphate. These compounds can be made in accordance with known procedures, or variations thereof which will be apparent to those skilled in the art. For example, phosphorylation of nucleosides by standard methods such as D. Hoard and D. Ott, J. Am. Chem. Soc. 87, 1785-1788 (1965); M. Yoshikawa, et al., Tetrahedron Lett. 5065-68 (1967) and idem., Bull. Chem. Soc. (Jpn) 42, 3505-08 (1969); J. Moffatt and H. Khorana, J. Am. Chem. Soc. 83, 649-59 (1961); and B. Fischer, et al., J. Med. Chem. 36, 3937-46 (1993) and references therein. Etheno derivatives of cytidine and adenosine are prepared by known methods such as: N. Kotchetkov, et al., Tetrahedron Lett. 1993 (1971); J. Barrio, et al., Biochem. Biophys. Res. Commun. 46, 597 (1972); J. Secrist, et al., Biochemistry 11, 3499 (1972); J. Bierndt, et al., Nucleic Acids Res. 5, 789 (1978); K. Koyasuga-Mikado, et al., Chem. Pharm. Bull. (Tokyo) 28, 932 (1980). Derivatives with alpha, beta and gamma thiophosphorus groups can be derived by the following or by adapting methods of: J. Ludwig and F. Eckstein, J. Org. Chem. 54, 631-35 (1989); F. Eckstein and R. Goody, Biochemistry 15, 1685 (1976); R. Goody and F. Eckstein, J. Am. Chem. Soc. 93, 6252 (1971).
Compounds of Formulas I, II, or III where R1 is CCl2 and CF2 can be prepared by methods similar to that described in G. Blackburn, et al., J. Chem. Soc. Perkin Trans. I, 1119-25 (1984). Compounds of Formula I, II, III where R1 is CH2 can be prepared by methods similar to that described in T. Myers, et al., J. Am. Chem. Soc. 85, 3292-95 (1963).
Compounds illustrative of the compounds of Formula IV include (P1,P4-di(adenosine-5xe2x80x2) tetraphosphate (A2P4) or P1,P4-di(uridine-5xe2x80x2) tetraphosphate (U2P4). These compounds can be made in accordance with known procedures, or variations thereof which will be described by: P. Zamecnik, et al., Proc. Natl. Acad. Sci. USA 89, 838-42 (1981); and K. Ng and L. E. Orgel, Nucleic Acids Res. 15 (8), 3572-80 (1987).
In addition, UTP, ATP, CTP, A2P4, 3,N4-ethenocytidine triphosphate, 1,N6-ethenoadenine triphosphate, adenosine 1-oxide triphosphate, ATPxcex3S, ATPxcex2S, ATPxcex1S, AMPPCH2P, AMPPNHP, N4-ethenocytidine and 1,N6-ethenoadenosine are commercially available, for example, from Sigma Chemical Company, PO Box 14508, St. Louis, Mo. 63178.
The active compounds of Formulae I-IV may be administered by themselves or in the form of their pharmaceutically acceptable salts, e.g., an alkali metal salt such as sodium or potassium, an alkaline earth metal salts such as manganese, magnesium and calcium or an ammonium and tetraalkyl ammonium salts, NX4+ (wherein X is C1-4). Pharmaceutically acceptable salts are salts that retain the desired biological activity of the parent compound and do not impart undesired toxicological effects.
The active compounds disclosed herein may be administered to the middle ear of a patient to promote fluid drainage in otitis media by a variety of suitable means, but are preferably administered by administering a liquid/liquid suspension (either a nasal spray of respirable particles which the subject inhales, or nasal drops of a liquid formulation) comprised of the active compound. Liquid pharmaceutical compositions of the active compound for producing a nasal spray or nasal drops may be prepared by combining the active compound with a suitable vehicle, such as sterile pyrogen free water or sterile saline by techniques known to those skilled in the art.
The dosage of active compound to promote fluid drainage will vary depending on the condition being treated and the state of the subject, but generally an effective amount is the amount sufficient to achieve concentrations of active compound on the middle ear surfaces of the subject of from about 10xe2x88x927 to about 10xe2x88x922 Moles/liter, and more preferable from about 10xe2x88x926 to about 3xc3x9710xe2x88x924 Moles/liter.
Depending upon the solubility of the particular formulation of active compound administered, the daily dose to promote fluid drainage may be divided among one or several unit dose administrations. Preferably, the daily dose is no more than two times per day.
Another means of administering the active compound to the middle ear of the patient to promote fluid drainage may include any oral form of the active compound, administered to the patient either by means of a liquid suspension of the active compound which is poured into the mouth of the patient, or by means of a pill form swallowed by the patient.
Another means of administering an effective amount of the active compound to the middle and inner ear would involve the patient inhaling a nebulized form of the active compound into their respiratory tract, such that the active compound enters the nasopharnyx and subsequently enters the inner and middle ear of the patient.
Another means of administering the active compound to the middle ear would include any topical form of the active compound, administered as a cream or gel to the outer ear, which would subsequently permeate through the tympanic membrane into the middle ear of the patient.
Another means of administering the active compound to the middle ear would involve an injected form of the active compound, injected from the outer ear directly through the tympanic membrane into the middle ear, or injected indirectly through the upper neck region into the middle ear.
Another means of administering the active compound to the middle ear would involve a suppository form of the active compound, such that a therapeutically effective amount of the compound reaches the middle ear via systemic absorption.
An additional means of administering the active compound would involve intra-operative instillation of the active compound into the middle, inner or outer ear via a gel, cream, or liquid suspension form of the active compound, such that a therapeutically effective amount reaches the middle, inner or outer ear.
UTP and compounds of Formulae I-IV also have therapeutic benefit when used in combination with other agents used to treat otitis media, such as, but not limited to: antibiotics like penicillin, penicillan plus beta-lactam, erythromycin plus sulisoxazole, cephalosporin, trimethoprim, trimethoprim plus sulfamethoxazole, macrolides, and oxazolidinones; vaccines; antihistamines, decongestants, mucolytic agents; nonsteroidal antiinflammatory agents; and corticosteroids. UTP may also be used in combination with agents under development, such as NE-1530xe2x80x94a naturally occuring airway oligosaccharide (Neose Technologies, Inc.), and gene therapy.
The present invention is explained in greater detail in the Examples which follow. These examples are intended as illustrative of the invention, and are not to be taken as limiting thereof.